JPH08201425A - Semiconductor acceleration detector - Google Patents

Abstract

(57) [Summary] [Construction] The base 5 electrically and mechanically connected to the electrode 10 on the base 6 by the conductive adhesive 9, and the base 5 electrically connected by the conductive adhesive 8 in a cantilever manner. Further, the semiconductor chip 1 mechanically connected thereto and the strain gauge 4 for detecting the strain of the semiconductor chip 1 caused by the acceleration applied to the object to be measured are provided, and the electrode 10 is connected to the pedestal 5 via the wire 11. A peeling detection current is passed through the semiconductor chip 1 to the wire 12 connected to the GND terminal, and by detecting whether or not the current is flowing normally, the base 6, the pedestal 5, and the semiconductor chip 1 are detected. Detects whether or not peeling has occurred in the joint. [Effect] By detecting whether or not an electric current is flowing, peeling can be easily detected, and false acceleration can be prevented from being detected without noticing an abnormality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor acceleration detecting device, and more particularly to a semiconductor acceleration detecting device mounted on an object to be measured such as an automobile and detecting an acceleration applied thereto.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional semiconductor acceleration detecting device. As shown in FIG. 9, in the conventional semiconductor acceleration detection device, a semiconductor chip 1 made of silicon or the like is cantilevered, one end 1b thereof is fixed to a pedestal 5, and the other end 1c is a free end. It is fixed to a base 6 attached to the object to be measured and is used for detecting acceleration of the object to be measured.
As shown in the figure, the semiconductor chip 1 has one end 1c which is a free end.
The strain gauge 4 includes a weight portion 2 provided in the thin wall portion 3, a thin portion 3 and a strain gauge 4 provided in the thin portion 3.
Is connected to an external electric circuit (not shown) via a wire 7. Here, in order to improve the sensitivity of the strain gauge 4 for detecting the strain of the semiconductor chip 1, the thin portion 3 is
As shown in the figure, a part of the semiconductor chip 1 is thinned.

The operation will be described. When the acceleration a is applied to the base 6 attached to the object to be measured, the acceleration a is also applied to the semiconductor chip 1 via the pedestal 5. Then, a force F = ma is generated in the weight portion 2 when the mass of the weight portion 2 is m. Since the weight portion 2 is formed integrally with the thin portion 3 and is supported by the thin portion 3, a stress corresponding to the force F is generated in the thin portion 3. This stress changes the resistance value of the strain gauge 4, so that the acceleration a applied to the object to be measured is detected by converting the change in the resistance value into an electric signal.

[0004]

As described above, in the conventional semiconductor acceleration detecting device, the acceleration a applied to the object to be measured is transmitted to the semiconductor chip 1 via the base 6 and the pedestal 5. Therefore, when the joint between the base 6 and the pedestal 5 or the joint between the pedestal 5 and the semiconductor chip 1 is incomplete, the acceleration a is not accurately transmitted to the semiconductor chip 1 and erroneous acceleration is not recognized as abnormal. There was a problem of measuring. Further, when the joints are completely peeled off, there is a problem that the acceleration a cannot be detected at all even though the acceleration a is applied to the object to be measured.

The present invention has been made to solve the above problems, and immediately detects the peeling that has occurred in the bonding between the base and the pedestal and the bonding between the pedestal and the semiconductor chip,
An object of the present invention is to obtain a semiconductor acceleration detecting device for notifying the system side or the user in advance that the acceleration to be detected cannot be accurately measured due to the peeling.

[0006]

According to a first aspect of the present invention, there is provided a substrate fixed to an object to be measured and having a conducting means on its surface, a semiconductor or a conductor, and electrically and mechanically connected to the conducting means. A pedestal, a beam electrically and mechanically connected to the pedestal, an acceleration detection means mounted on the beam for detecting an acceleration by a shake of a weight due to an acceleration applied to an object to be measured, and a substrate Continuity means, a constant current source for peeling detection for flowing a constant current for peeling detection through the path of the pedestal and the beam, and whether or not the current for peeling detection flows in the path is detected, and as a result, Connection between the board and the pedestal,
Alternatively, and / or, the semiconductor acceleration detecting device is provided with a peeling detection means for detecting whether or not peeling has occurred in the connection between the pedestal and the beam.

According to a second aspect of the present invention, there is provided a semiconductor acceleration detecting device provided with a conductive means of the substrate, a pedestal, and a conductive joint means having electrical conductivity for joining the beam.

A third aspect of the present invention is the semiconductor acceleration detecting device, wherein the conductive joining means is a conductive adhesive.

A fourth aspect of the present invention is the semiconductor acceleration detecting device, wherein the conductive joining means is solder or a conductive brazing material.

According to a fifth aspect of the present invention, there is provided a semiconductor acceleration detecting device in which the acceleration detecting means and the peeling detecting means are constituted by one chip.

A sixth aspect of the present invention is a semiconductor acceleration detecting device in which the acceleration detecting means and the peeling detecting means are respectively constituted by separate chips.

According to a seventh aspect of the present invention, the peeling detection means includes a reference voltage generating section for outputting a reference voltage, a voltage depending on a resistance value of the path when the peeling detection current flows, and the reference voltage. The voltage levels are compared and judged, and from the results,
The semiconductor acceleration detecting device includes a comparison and determination unit that outputs a comparison and determination signal that indicates whether or not a current is flowing normally.

According to an eighth aspect of the present invention, the separation detecting means comprises a pair of PNP transistors, and the collector current of the PNP transistor changes depending on the resistance value of the separation detection current path. And a NPN transistor whose conduction is controlled based on the collector current value of the current mirror circuit section, which is a semiconductor acceleration detecting device which outputs the level of the collector potential of the NPN transistor.

[0014]

According to the invention of claim 1, a constant current source for peeling detection is provided, and a constant current for peeling detection is passed through the conducting means, the pedestal and the beam provided on the substrate, and the peeling detection means provides By detecting whether or not the constant current normally flows, it is detected whether or not peeling has occurred in the bonding between the substrate, the pedestal and the beam.

According to the second aspect of the present invention, since the substrate, the pedestal and the beam are electrically and mechanically joined by the conductive joining means having conductivity, the constant current for peeling detection passes through the conductive joining means. Flow to the substrate, pedestal and beams.

According to the third aspect of the invention, since the conductive adhesive is used as the conductive joining means, it is directly applied to both surfaces of the pedestal and the surface of the conducting means, and is cured by heat treatment or the like, whereby the manufacturing process is performed. Easy and strong joining.

In the invention of claim 4, since the solder or the brazing material is used as the conductive joining means, the joining means is hardened immediately after joining, so that the manufacturing process is easy and the time required for it is short. .

According to the invention of claim 5, the acceleration detecting means and the peeling detecting means are constituted by one chip, so that the apparatus is miniaturized.

In the invention of claim 6, since the acceleration detecting means and the peeling detecting means are respectively constituted by separate separate chips, the acceleration detecting means and the peeling detecting means are manufactured separately and the reliability test is carried out. And combine the passed products to commercialize.

According to the seventh aspect of the invention, the peeling detection means is constituted by the comparison / determination unit for performing the comparison / determination of the voltage depending on the resistance value of the flow path for the peeling detection current and the reference voltage. In the manufacturing process, the conductive means of the substrate that serves as the flow path for the separation detection, the individual resistance values of the pedestal, the beam, and the like do not have to be manufactured with high accuracy, but accurately and immediately,
Detect peeling.

According to another aspect of the present invention, the peeling detection means is configured by using a current mirror circuit section, and the NPN transistor is opened / closed by the collector current value of the current mirror circuit section, and the collector of the NPN transistor is opened. The potential level is used as the output of the peeling detection means.

[0022]

【Example】

Example 1. FIG. 1 shows an embodiment of the present invention. As shown in the figure, in this embodiment, an electrode 10 which is a conducting means for fixing a pedestal 5 for supporting the semiconductor chip 1 in a cantilever manner is a base 6 which is a substrate attached to the object to be measured. It is provided above. The electrode 10 is, for example, A
It is formed of a thick film conductor made of gPd or AgPt. The pedestal 5 is made of a semiconductor such as silicon, and is joined to the electrode 10 by a conductive adhesive 9 as shown in the figure. Similarly, the pedestal 5 and the semiconductor chip 1 are joined by the conductive adhesive 8. The conductive adhesives 8 and 9 constitute the conductive bonding means in this embodiment, and for example, an epoxy-based adhesive mixed with silver powder is suitable, but not limited to this case, the bonding property may be improved. Any material may be used as long as it has conductivity.
The pedestal 5 is not limited to a semiconductor, and may be formed of a conductor such as metal.

Further, as shown in FIG. 1, a constant current source 18
(See FIG. 2) and wire 1 for flowing a current from the constant current source 18 to the electrode 10 and wire 1 for connecting the semiconductor chip 1 to the ground terminal 21 (see FIG. 2).
2 and are provided. Also, in this embodiment,
A signal processing circuit unit (not shown) for converting a resistance value change generated in the strain gauge 4 into an electric signal is provided in a portion 1a of the semiconductor chip 1 on the side closer to the base 5. The other structure is similar to that of the conventional example shown in FIG. 9, and therefore its description is omitted here. The semiconductor chip 1 in this embodiment is electrically and mechanically connected to the pedestal 5 to form a beam for supporting the weight 2, and the strain gauge 4 is applied to the object to be measured. The acceleration detecting means is configured to detect the acceleration applied to the object to be measured by the shake of the weight 2 due to the acceleration.

FIG. 2 is a sectional view showing in detail the structure of the semiconductor acceleration detecting device of FIG. As shown in FIG. 2, the semiconductor chip 1 is composed of a P-type substrate 13, an n ⁻ epitaxial layer 14, and a P-type isolation layer 20 provided between the n ⁻ epitaxial layers 14. An oxide film 15 for insulation is provided on the semiconductor chip 1, and an electrode 16 and an electrode 19 are provided on the oxide film 15. The electrode 16 is made of aluminum and is connected to the wire 11, and the electrode 19 is also made of aluminum and is connected to the wire 12. Also,
The entire surface of the semiconductor chip 1 including the oxide film 15, the electrodes 16 and the electrodes 19 is covered with a glass layer 17 for surface protection except for a part for connection with the wires 11 and 12 and the like. There is. Further, as described above, the constant current source 18 for discharging the current is connected to the electrode 16, and the electrode 19 is connected to the ground terminal 21 via the wire 12.
It is connected to the. Here, the power supply 29, the constant current source 18, and the ground terminal 21 constitute a separation detection constant current source means for supplying a constant current to the electrode 10 of the base 6, the pedestal 5, and the semiconductor chip 1.

In FIG. 2, R ₁ , R ₂ , R ₃ and R ₄ are the resistance value of the conductive adhesive 9 and the pedestal 5, respectively.
2 and the resistance value of the conductive adhesive 8 and the resistance values of the P-type substrate 13 and the P-type separation layer 20 are shown in the figure for convenience.

The operation will be described. Since the operation of detecting the acceleration of the object to be measured using the strain gauge 4 is the same as that shown in the conventional example, the description thereof is omitted here. Therefore, here, only the peeling detection operation for detecting whether or not peeling has occurred in the bonding between the base 6 and the pedestal 5 and the bonding between the pedestal 5 and the semiconductor chip 1, which is a feature of the present invention, will be described. To do. First, as shown in FIG. 2, a current I _0, which is a constant current for peeling detection, ejected from the constant current source 18 flows to the wire 11 through the electrode 16. Since the wire 11 is connected to the electrode 10, the current I ₀ flows to the electrode 10 and further to the pedestal 5 from the electrode 10 via the conductive adhesive 9, and further to the conductive adhesive 8
Through to the P-type substrate 13. The P-type substrate 13 is P
Since it is connected to the electrode 19 via the shape separation layer 20, the current I ₀ flows into the electrode 19 and flows to the ground terminal 21 via the wire 12 connected to the electrode 19. As described above, the current I ₀ flows to the ground 21 through the pedestal 5, the P-type substrate 13, and the like.

However, when the pedestal 5 and the base 6 are separated, and / or the semiconductor chip 1 and the pedestal 5 are separated, the path through which the current I ₀ flows is cut off. I ₀ does not flow to the ground terminal 21. Therefore, by detecting whether or not the current I ₀ is flowing, peeling of the pedestal 5 and the base 6 and the semiconductor chip 1 and the pedestal 5 can be easily detected.

FIG. 3 shows a specific structure of the peeling detecting means for detecting whether or not the current I ₀ is flowing and detecting the peeling. The peeling detection means 50A is composed of a comparator 26 which is a comparison determination unit and a reference power supply 27 which is a reference voltage generation unit for generating the reference voltage Vref, and a portion 1a of the semiconductor chip 1 near the pedestal 5a. And the signal processing circuit section (not shown) described above. As described above, in this embodiment, the acceleration detecting means and the peeling detecting means, which are the strain gauges 4, are constituted by one chip. In the figure, 22, 23, 24 and 25 are respectively the above-mentioned conductive adhesive 9 (resistance value R
₁ ), pedestal 5 (resistance value R ₂ ), conductive adhesive 8 (resistance value R ₃ ), and resistance corresponding to P-type substrate 13 and P-type separation layer 20 (resistance value R ₄ ). In the comparator 26, the voltage drop generated in the resistors 22 to 25 when the current I ₀ from the constant current source 18 is passed through the resistors 22 to 25, that is, I _0.
(R ₁ + R ₂ + R ₃ + R ₄ ) and the reference voltage Vref output from the reference power supply 27 are input, the comparator 26 makes a comparison determination of them, and a comparison determination signal VCO indicating the result.
Output M.

Since the resistance values R ₁ , R ₂ , R ₃ and R ₄ of the resistors 22 to 25 are substantially determined by the material and structure thereof, the current I ₀ and the reference voltage Vref are set to I _{0 as} follows. If (R ₁ + R ₂ + R ₃ + R ₄ ) <Vref (Equation 1) is set, the output of the comparator 26 becomes “L” level. Here, if the base 5 and the base 6 are separated, R ₁ ≈∞
Therefore, I ₀ (R ₁ + R ₂ + R ₃ + R ₄ )> Vvef (Equation 2), and the comparison determination signal VCO output from the comparator 26
M becomes "H" level.

Similarly, when the pedestal 5 and the semiconductor chip 1 are separated, R ₃ ≉∞, so that in this case as well, the comparator 2
The comparison determination signal VCOM output from 6 becomes "H" level.

As described above, in this embodiment, when the comparison determination signal VCOM output from the comparator 26 becomes the "H" level, the base 5 and the base 6 or the base 5 are used.
Since the junction between the semiconductor chip 1 and the semiconductor chip 1 is peeled off and the current I ₀ does not flow, the system side or the user peels off the peeling by checking the level of the comparison determination signal VCOM output from the comparator 26. Can be detected easily and immediately, and erroneous acceleration of the object to be measured can be prevented from being measured without noticing that it is abnormal.

Further, by using the comparator 26, the resistors 22 to 2
The voltage drop across the 5 performs a comparison determination between the reference voltage Vref, the result, since so as to detect whether or not peeling occurs, the resistance value R ₁ in the manufacturing process
Even if the values of R ₄ to R ₄ are not manufactured with high accuracy, the peeling can be accurately detected, so that the manufacturing process is facilitated and the manufacturing can be performed at low cost.

Example 2. FIG. 4 shows a current I ₀ in the acceleration detecting device of the present invention having the structure shown in FIGS. 1 and 2.
5 shows another example of the peeling detecting means for detecting whether or not the flow is flowing and detecting peeling. As shown in FIG. 4, the peeling detection means 50B in this embodiment is similar to that shown in FIG.
Of the constant current source 18 instead of the resistor 2 having a resistance value R ₀
8 (resistance value R ₀ ) is provided. Further, in the figure, 29 is a power supply, and the power supply voltage is Vcc.
Other structures are similar to those of the embodiment shown in FIG. At this time,

[0034]

[Equation 1]

So that the resistance R ₀ and the reference voltage V
Set ref. In this case, in the comparator 26, which is the comparison / determination unit, the power supply voltage Vcc of the power supply 29 is set to the resistance 28.
And the voltage divided by the resistors 22 to 25 and the reference voltage Vre
The comparison determination with f is performed, and the comparison determination signal VCOM indicating the result is output. Therefore, the comparison determination signal VCOM output from the comparator 26 is normally at the “L” level, but when the pedestal 5 and the base 6 are separated, the resistance value R _{1 of} the conductive adhesive 9 portion becomes ∞. Therefore, if the above (Formula 3) is modified so that R ₁ ≈∞,

[0036]

[Equation 2]

Then, the comparison judgment signal VCOM output from the comparator 26 becomes "H" level. Further, when the pedestal 5 and the semiconductor chip 1 are separated, the resistance value R _{3 of} the conductive adhesive 8 portion becomes ∞, and similarly, the comparison determination signal VCOM output from the comparator 26 becomes “H” level. .

As described above, also in this embodiment, as in the above-described first embodiment, when the comparison determination signal VCOM output from the comparator 26 becomes "H" level, the pedestal 5 and the base 6 are provided. Alternatively, since the joint between the pedestal 5 and the semiconductor chip 1 is peeled off, the system side or the user can easily and immediately detect the peeling by the comparison determination signal VCOM output from the comparator 26. Therefore, it is possible to prevent erroneous acceleration of the measured object from being measured without noticing that it is abnormal.

Also in this embodiment, the resistance value R of the resistor 28 and the resistors 22 to 25 is the same as in the above-described first embodiment.
_{Even if} the accuracy of _{0 to} R ₄ is not so high, the structure is such that the peeling can be accurately detected, so that the manufacturing process is easy and the manufacturing cost can be low.

Example 3. FIG. 5 shows a current I ₀ in the acceleration detecting device of the present invention having the structure shown in FIGS. 1 and 2.
6 shows another example of the peeling detection means for detecting whether or not the flow is flowing. Delamination detection means 5 in this embodiment
At 0C, as shown in the figure, a pair of PNP transistors 30 and 31 are provided, and the bases and emitters of these PNP transistors 30 and 31 are common, and these constitute a current mirror circuit section. In addition, PNP
The transistors 30 and 31 have the same size. Reference numeral 32 is a resistor connected to the collector of the PNP transistor 30, and its resistance value is R ₅ . Resistance 32
Need not always be provided, and may be provided as needed. Further, 33 is a PNP transistor 31.
Is a resistor connected to the collector of and its resistance value is R ₆
Is. Furthermore, an NPN transistor 34 whose base is connected between the collector of the PNP transistor 31 and the resistor 33, and a load resistor 35 of the NPN transistor 34.
Are provided.

At this time, the collector current I _C1 of the PNP transistor 30 is given by the following (formula 5) when the base-emitter voltage of the PNP transistor 30 is V _BE30 .

[0042]

(Equation 3)

Further, the collector current I _C2 of the PNP transistor 31 becomes I _C2 ≈I _C1 (Equation 6) due to the action of the current mirror circuit section composed of the pair of PNP transistors 30 and 31. Therefore, the voltage drop V _R33 across the resistor 33 is

[0044]

[Equation 4]

It becomes Further, the voltage V _{BE (ON) 34} for turning on the NPN transistor 34 is compared with the above voltage drop V _R33 so that the voltage V _{BE (ON) 34} becomes V _R33 ≧ V _{BE (ON) 34.} If set, the NPN transistor 34 is ON in a normal state and the collector potential of the NPN transistor 34 becomes "L". That is,

[0046]

(Equation 5)

Then, the collector potential becomes "L" level. The collector potential is the output VCOM of the detection means 50C in this embodiment.

When the pedestal 5 and the base 6 are separated, the resistance value R _{1 of} the conductive adhesive 9 portion becomes ∞,
The above (Formula 8) is

[0049]

(Equation 6)

Then, the NPN transistor 34 is turned off.
However, the collector potential becomes "H" level. Even when the semiconductor chip 1 and the pedestal 5 are separated from each other, the resistance value R _{3 of} the conductive adhesive 8 portion becomes ∞, and the collector potential of the NPN transistor 34 also becomes “H” level. In this way, the pedestal 5 and the base 6 or the semiconductor chip 1
It is possible to easily detect peeling between the pedestal 5 and the pedestal 5.

As described above, also in this embodiment, the same effects as those of the above-described first and second embodiments can be obtained, and
Also in this embodiment, since the circuit configuration is simplified,
It can be manufactured easily and inexpensively.

Example 4. FIG. 6 shows another embodiment of the present invention. This embodiment corresponds to the above-mentioned first to third embodiments.
Instead of the conductive adhesives 8 and 9 (see FIG. 1), the brazing materials 36 and 37 having conductivity such as solder, gold silicon, or gold tin are used, and the semiconductor chip 1, the pedestal 5, the electrode 10, and the pedestal 5 are used. It is designed to be joined with. In this case, in order to improve solderability or brazability, it is necessary to form a metal thin film (not shown) on the back surface of the semiconductor chip 1 and both surfaces of the pedestal 5 by vapor deposition or sputtering. is there. As an example of this metal thin film, for example, three layers of Ti—Ni—Au may be formed so that the outermost layer is Au which is excellent in solderability and brazability.

The pedestal 5 does not necessarily have to be made of silicon, but may be made of a metal such as copper or iron. In that case, it is not necessary to apply the metal thin film formed by the above-described vapor deposition method or sputtering method to both sides of the pedestal 5, and soldering or brazing can be performed as it is, so that the manufacturing process is further facilitated. Become.

In this embodiment, the solder or brazing materials 36 and 37 have the same function as the conductive adhesives 8 and 9 of the first to third embodiments. The effect of is obtained. Further, when the conductive adhesives 8 and 9 are used for bonding, a curing step for curing the conductive adhesives 8 and 9 by heat treatment is required, so that it takes time in the manufacturing process. In this embodiment, since the solder or the brazing materials 36 and 37 are used for joining, they are hardened and hardened immediately, so that the curing step is unnecessary and the manufacturing process can be facilitated and the manufacturing process time can be shortened. it can.

Example 5. 7 and 8 show another embodiment of the present invention. The semiconductor acceleration detecting device in this embodiment basically has the same structure as that of the embodiment shown in FIG. The sectional view of FIG. 7 is a sectional view of the device taken from a position rotated by 90 ° with respect to the sectional view of FIG. In the above-described first to fourth embodiments, the semiconductor chip 1 includes the acceleration detecting means including the strain gauge 4 and the peeling detecting means 50A, 50B or 50C whose specific structural examples are shown in FIGS.
However, in the present embodiment, the acceleration detecting means and the peeling detecting means are separately configured by separate chips and separated from each other.

As shown in FIG. 7, the semiconductor acceleration detecting device in this embodiment is cantilevered to the pedestal 5 by the conductive adhesive 8 and the weight 2 (see FIG. 1) is formed at the free end. Further, the strain gauge 4 (see FIG. 9) is provided in the thin portion 3 (see FIG. 1), and the semiconductor chip 38 made of silicon and the strain detected by the peeling detection means and the strain gauge 4 are converted into an electric signal. It is composed of an IC chip 39 which constitutes a signal processing circuit section. The electrode 10 bonded to the pedestal 5 and the IC chip 39 are connected by a wire 45. Further, in the semiconductor chip 38, an n ⁺ diffusion layer 40b is formed in an n layer 40a, and the n ⁺ diffusion layer 40b is connected to the power source 29 by wiring 4 such as Al wiring.
Connected by 6. Further, in FIG. 8, the n layer 40a portion of the semiconductor chip 38 is shown as a resistor 41,
Let the resistance value be R ₆ . In the IC chip 39, a constant current source (suction type) 43, a comparator 26, and a reference voltage V
A reference power supply 27 that outputs ref is provided. Here, the comparator 26 and the reference power supply 27 constitute the peeling detection means 50D in this embodiment.

[0057] Incidentally, in this embodiment, the semiconductor chip 38 in relation to an n layer 40a, instead of the discharge type constant current source 18 to flow out current shown in FIG. 2, the suction draws in current I ₀ Type constant current source 43 is used. That is, when the semiconductor chip 38 is composed of a P-type substrate, the outflow type constant current source 1 is used as in the embodiment of FIG.
8 may be used. Here, the constant current source means for peeling detection in this embodiment includes a power source 29 and a constant current source 4.
3 and the ground terminal 21. As shown in FIG. 7, the current I ₀ is applied to the n layer 40 a of the semiconductor chip 38.
Flow through the conductive adhesive 8, the pedestal 5, the conductive adhesive 9, the electrode 10, and the wire 45 to the IC chip 39. If the pedestal 5 and the base 6 are separated, and / or the semiconductor chip 38 and the pedestal 5 are separated, the path through which the current I ₀ flows is cut off there, so that the current I ₀ is removed. Does not flow to the ground terminal 21. Therefore, also in this embodiment, the peeling of the pedestal 5 and the base 6, and the semiconductor chip 38 and the pedestal 5 can be detected by constantly detecting whether or not the current I ₀ is flowing.

Here, the current value I ₀ and the reference voltage Vref
The value of Vcc-I ₀ × (R ₆ + R ₃ + R ₂ + R ₁ )> Vref (Equation 10) is set, and the voltage effect Vcc-I ₀ generated in the resistors 22, 23, 24, and 41 is set. × (R ₆ + R ₃ + R ₂ +
When the comparator 26 compares and determines R ₁ ) and the reference voltage Vref, the comparison determination signal VCOM output from the comparator 26 is "L" level in a normal state.

However, here, the base 6 and the pedestal 5
When and are peeled off, the resistance value R ₁ of the conductive adhesive 9 becomes ∞. Therefore, the above (Formula 10) is Vcc-I ₀ × (R ₆ + R ₇ + R ₁ + R ₃ ) <Vref (Formula 11) And the comparison determination signal VCO output from the comparator 26
M becomes "H" level. When the pedestal 5 and the semiconductor chip 38 are separated, the resistance value R _{3 of the} conductive adhesive 8 is increased.
Becomes ∞, and similarly, the comparison / determination signal VCOM becomes “H” level.

As described above, also in this embodiment, as in the above-described first embodiment, when the comparison determination signal VCOM output from the comparator 26 becomes the "H" level, the base 5 and the base 6 are provided. Alternatively, since the junction between the semiconductor chip 38 and the pedestal 5 is peeled off, the system side or the user can easily and immediately detect the peeling off by the comparison determination signal VCOM output from the comparator 26. Therefore, it is possible to prevent erroneous acceleration of the object to be measured without noticing that it is abnormal.

In general, since it is difficult to manufacture the thin portion 3 formed on the semiconductor chip 38 with high accuracy, the semiconductor chip 38 having the acceleration detecting means including the strain gauge 4 and the thin portion 3 is more preferable. Since the yield is lower than that of the IC chip 39 having the peeling detecting means, when the acceleration detecting means and the peeling detecting means are constituted by one chip,
Even if the peeling detection means is acceptable, if the acceleration detection means is defective, both of them must be discarded. In this embodiment, the semiconductor chip 38 provided with the acceleration detection means, Since the IC chip 39 having the peeling detection means is configured as a separate body, the IC chip 39 and the semiconductor chip are manufactured separately in the manufacturing process, and the reliability test is performed individually for each, and the product passes Since it suffices to combine them, it is not necessary to discard the peeling detection means of the acceptable product because the acceleration detection means is defective, and the amount of peeling detection means to be discarded can be reduced accordingly, and the yield can be improved. it can. As a result, the manufacturing cost is not wasted and the product can be made inexpensive.

In the first to fifth embodiments described above, the semiconductor chip 1 forming the beam is provided on the pedestal 5 in a cantilever manner and the strain detecting type acceleration detecting device using the strain gauge 4 is used. However, not limited to that case,
The acceleration detection device of the present invention can be applied to a double-supported type of beam, a displacement detection type acceleration detection device which detects acceleration by displacement instead of strain.

[0063]

According to the first aspect of the present invention, the peeling detection constant current source means is provided, and the peeling detection constant current is caused to flow through the conducting means provided on the substrate, the pedestal, and the beam. By detecting whether or not the constant current is flowing normally, it is possible to detect whether or not peeling has occurred in the bonding of the substrate, pedestal and beam, so that peeling can be detected easily and reliably. There is an effect that can be done.

According to the second aspect of the present invention, since the substrate, the pedestal and the beam are electrically and mechanically joined by the conductive joining means having conductivity, the constant current for peeling detection passes through these conductive joining means. Since the current flows to the substrate, the pedestal, and the beam, the peeling detection current easily flows under normal conditions, and when peeling occurs, it becomes difficult for the peeling detection current to flow, so that peeling can be clearly detected. .

According to the third aspect of the present invention, since the conductive adhesive is used as the conductive joining means, it is directly applied to both surfaces of the pedestal and the surface of the conducting means, and is cured by heat treatment or the like, so that the manufacturing process is performed. There is an effect that it can be easily made and can be firmly joined so that peeling does not easily occur.

According to the invention of claim 4, since the solder or the brazing material is used as the conductive joining means, the joining means is hardened immediately after joining, so that the manufacturing process is easy and the joining can be performed firmly and at the same time. This has the effect of shortening the time required for the process.

According to the invention of claim 5, the acceleration detecting means and the peeling detecting means are constituted by one chip, so that there is an effect that the apparatus can be downsized.

In the invention of claim 6, since the acceleration detecting means and the peeling detecting means are respectively constituted by separate chips, the acceleration detecting means and the peeling detecting means are manufactured separately and the reliability test is performed. Since it was made to combine the passed products to produce a product, it is possible to improve the yield because one product is defective and the other product that is a passing product is not discarded. Play.

According to the invention of claim 7, the peeling detecting means is constituted by a comparison / judgment unit for making a judgment of comparison between the voltage depending on the resistance value of the flow path for the peeling detection current and the reference voltage. In the manufacturing process, it is possible to detect the peeling reliably and immediately without manufacturing the resistance values of the substrate, which is the flow path of the peeling detection current, the individual resistance values of the pedestal, the beam, and the like with high accuracy. The manufacturing process is facilitated and the manufacturing cost can be reduced.

According to the invention of claim 8, the peeling detecting means is constituted by using a current mirror circuit section, and the NPN transistor is opened / closed according to the value of the collector current of the current mirror circuit section, and the collector of the NPN transistor is opened. Since the potential level is used as the output of the peeling detection means, the circuit has a simple structure and can be manufactured easily and inexpensively.

[Brief description of drawings]

FIG. 1 is a perspective view showing a semiconductor acceleration detection device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view showing the structure of the semiconductor acceleration detection device of FIG.

FIG. 3 is an equivalent circuit diagram showing a configuration of peeling detection means of the semiconductor acceleration detection device of FIG.

FIG. 4 is an equivalent circuit diagram showing a configuration of a peeling detection means of a semiconductor acceleration detection device according to a second embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram showing a configuration of a peeling detecting means of a semiconductor acceleration detecting device according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing a structure of a semiconductor acceleration detection device according to a fourth embodiment of the present invention.

FIG. 7 is a sectional view showing a structure of a semiconductor acceleration detection device according to a fifth embodiment of the present invention.

8 is an equivalent circuit diagram showing a configuration of a peeling detection means of the semiconductor acceleration detection device of FIG.

FIG. 9 is a sectional view showing a structure of a conventional semiconductor acceleration detection device.

[Explanation of symbols]

1 semiconductor chip, 4 strain gauges, 5 pedestals, 8, 9
Conductive adhesive, 18,43 constant current source, 26 comparator,
27 reference power source, 30, 31 PNP transistor, 3
4 NPN transistor, 36, 37 Solder or brazing material.

Claims (8)

[Claims] 1. A substrate fixed to an object to be measured, having a conducting means on its surface, a pedestal made of a semiconductor or a conductor, electrically and mechanically connected to the conducting means, and an electrical and mechanical means for the pedestal. Beam connected to the beam, a weight supported by the beam, and an acceleration detection unit mounted on the beam and configured to detect the acceleration by the shake of the weight due to the acceleration applied to the object to be measured. A constant current source for peeling detection for passing a current for peeling detection through the path of the conduction means, the pedestal and the beam, and detecting whether or not the current for peeling detection flows in the path. According to the result, peeling detection means for detecting whether or not peeling has occurred in the connection between the substrate and the pedestal, and / or the connection between the pedestal and the beam, Half equipped with Body acceleration detecting device. 2. The semiconductor acceleration detecting device according to claim 1, further comprising conductive connecting means having conductivity for connecting the conducting means of the substrate, the pedestal and the beam. . 3. The semiconductor acceleration detecting device according to claim 2, wherein the conductive joining means is a conductive adhesive. 4. The semiconductor acceleration detecting device according to claim 2, wherein the conductive joining means is a solder or a conductive brazing material. 5. The acceleration detecting means and the peeling detecting means are constituted by one chip.
5. The semiconductor acceleration detection device according to any one of 1 to 4. 6. The semiconductor acceleration detecting device according to claim 1, wherein the acceleration detecting means and the peeling detecting means are respectively constituted by separate chips. 7. The peeling detection means includes a reference voltage generator that outputs a reference voltage, and a voltage level of the reference voltage and a voltage that depends on the resistance value of the path when the peeling detection current flows. 7. A comparison / determination unit that performs a comparison / determination and outputs a comparison / determination signal indicating whether or not the current is flowing normally based on the result of the comparison / determination.
The semiconductor acceleration detection device according to any one of 1. 8. The current mirror circuit section, wherein the peeling detection means comprises a pair of PNP transistors, and a collector current of the PNP transistor changes depending on a resistance value of a path of the peeling detection current. 7. An NPN transistor whose conduction is controlled based on the collector current value of the current mirror circuit section, and a level of the collector potential of the NPN transistor is output. The semiconductor acceleration detection device described.